JP2001228198A - Arrester deterioration detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arrester deterioration detector capable of accurately detecting deterioration of an element with a simple structure and detecting pollution of an insulator distinctively. SOLUTION: A selector 6 is controlled for measuring leakage current in three-phase arresters 1 so that a current in each phase or a three-phase composite current (zero-phase current) is measured. The measured current is transmitted to the detector via an optical fiber 8. In this way, the electric current measurement accuracy is improved and penetration of noise can be prevented. The detector 9 thermally corrects the measured electric current value. If the zero- phase current is increased above a predetermined control value, algorithm detecting a deterioration phenomenon of the element is used, while algorithm detecting an insulator pollution phenomenon is used when the zero-phase current is lowered below the control value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting deterioration of elements of an insulator type arrester (hereinafter, simply referred to as "arrestor") and contamination of the insulator used in a substation facility or the like.

[0002]

2. Description of the Related Art A conventional arrester deterioration detecting device always measures a leakage current using a leakage current transformer for each phase. When the measured leakage current value exceeds a predetermined management value (threshold value), it is determined that the arrester element has deteriorated.

[0003]

The conventional arrester deterioration detecting device has the following problems. 1. In order to constantly measure the leakage current of each phase arrester, it is necessary to take various noise countermeasures using an expensive leakage current transformer because the leakage current is very small. This makes the system complicated and expensive.

[0004] 2. Although the leakage current characteristics of the arrester element change due to the change in the outside air temperature, the influence of the change in the outside air temperature was not considered to be a significant problem in determining the deterioration of the arrester element. It was not reflected in the judgment value. However, when simultaneously detecting contamination of the insulator, it is necessary to remove disturbance factors such as temperature changes as much as possible.

[0005] 3. The arrester leakage current monitoring is used only for detecting element deterioration, and in many cases, insulator contamination cannot be monitored. In addition, when monitoring insulator contamination, it is necessary to distinguish between an increase in leakage current due to contamination and an increase / decrease in leakage current due to element deterioration. However, when element deterioration and insulator contamination are detected simultaneously, the phase of element deterioration is determined. Has not been established.

[0006] 4. Since the leakage current changes depending on the humidity and temperature, the degree of element deterioration and insulator contamination cannot be quantitatively grasped from the leakage current value. 5. When determining the management value of the element deterioration, the leakage current is measured after the operation is started, and the value is input as the initial value, which requires labor. 6. The signal transmission between the leakage current measuring means and the detecting means,
Since the wires are used, a failure due to surge, arrester discharge, noise, and the like are picked up by the wires, thereby lowering the S / N ratio and lowering the sensitivity.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an arrester deterioration detecting device capable of accurately detecting element deterioration with a simple configuration and further capable of distinguishing and detecting insulator contamination.

[0008]

The present invention employs the following means to achieve the above object. 1. Connect a low-impedance load with constant current bias to the light emitting diode as the load of the leakage current transformer,
By converting an electric signal to an optical signal and outputting the signal, a small leakage current can be measured at low cost and without noise.

[0009] 2. The leak current change of the arrester element due to the outside air temperature is corrected. 3. Insulators are basically contaminated in all phases at the same time, so if the multi-phase leakage current increases similarly, it is judged that the insulator is contaminated, and if only one phase changes specifically, the element is deteriorated. judge. 4. By using a humidity sensor and a temperature sensor together, the effects of humidity and temperature are corrected to leakage current.

[0010] 5. Various current values and management values (thresholds) to be automatically set at the start of operation are calculated. Specifically, assuming that the leakage current value at the time of drying is not affected by contamination by the combined use of the humidity sensor, the values at the time of drying are averaged, the initial leakage current value of the element is calculated, and the value is automatically reflected on the initial setting value. 6. The signal transmission between the measuring device and the detecting device uses signal insulation by an optical fiber to make it noise-free.

[0011]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a configuration of the arrester deterioration detection device. The arrester 1 is composed of an element 2 made of zinc oxide and an insulator 3
Housed inside. An arrester 1 for multiple phases is connected between the power line 4 and the ground. A current transformer 5 for detecting a leakage current is provided in the arrester 1 of each phase. The output of the current transformer 5 is input to the electric / optical converter 7 through the selector 6. The electrical / optical converter 7 converts the electrical signal into an optical signal, and the optical fiber 8
Is transmitted to the detection device main body 9. As described above, by performing the signal transmission through the optical fiber 8, a decrease in the S / N ratio can be prevented.

In the main body 9 of the detecting device, the optical signal transmitted by the optical fiber 8 is converted into an electric signal by the optical / electrical converter 11 and inputted to the detecting means 12. Detecting means 12
Further, a temperature measuring means 13 for measuring the outside air temperature, a humidity measuring means 14 for measuring the humidity, and a display section 15 for displaying the state of occurrence of element deterioration and insulator fouling are connected. The temperature measuring unit 13 and the humidity measuring unit 14 are arranged at a location around the arrester 1 where the temperature and the humidity are detected. Detecting means 12
Is configured by a CPU and executes various controls described below.

The selector 6 performs a switching operation of a leakage current measuring phase in accordance with a switching control signal sent from the detecting means 12. When one of the three switches of the selector 6 is turned on, a one-phase leakage current signal is generated by the electro-optical converter 7.
Is input to When all the switches of the selector 6 are turned on, a three-phase combining circuit is formed, and a zero-phase leakage current signal is input to the electro-optical converter 7. Thus, the selector 6
Is used, the number of optical fibers 8 can be reduced to only one irrespective of the number of phases of the arrester.

In the electro-optical converter 7, the output current of the selector 6 is converted by the light emitting diode 16 into an optical signal. Since the light emitting diode 16 has a relatively high resistance to a small current, a DC bias current is applied to the light emitting diode 16 in advance by the DC power supply 17. As a result, a minute leakage current on the order of microamps is accurately converted into an optical signal, and leakage current detection with high accuracy becomes possible.

The function of the detecting means 12 will be described with reference to FIG. The temperature T and the humidity H around the arrester 1 are measured by the temperature measuring means 13 and the humidity measuring means 14 by the first function F1. The leak current is measured by the second function F2. At this time, by switching the selector 6, the leakage current I for each of the three phases and the current of the three phases combined (zero-phase current)
Measure Io. Note that the effective value is measured as the measured value, but the peak value is also measured if necessary, as described later.

The third function F3 allows the temperature measuring means 13
The leak current value is corrected based on the outside air temperature measured in the step. FIG.
Shows a general temperature change characteristic curve of the capacitance component and the resistance component of the current density J of the zinc oxide element 2. As is clear from this, since the leakage current I changes depending on the temperature characteristics of the element 2, the measured leakage current I of each phase is corrected by the outside air temperature T to improve the reliability and accuracy of the measured value. The temperature-corrected leakage current value is represented by Ix.

The fourth function F4 shown in FIG.
4 is a predetermined management value (humidity management value) H
It is determined whether it is greater than n. When the humidity H falls below the humidity control value Hn, the leakage current due to the contamination of the insulator 3 becomes almost zero. Therefore, when the humidity H is equal to or less than the humidity management value Hn, the fifth function F5 records the temperature-corrected leakage current value Ix as the leakage current value Ixo at or below the humidity management value Hn.

When the humidity H exceeds the humidity control value Hn,
In the sixth function F6, the leakage current value Ixo immediately before exceeding the management value is stored at the same time as storing the leakage current value as Iy. FIG. 4 shows the result of managing the leakage current by humidity.
The horizontal axis of the figure indicates time, and one scale indicates one day.
(A) shows the leakage current I of one month's actual measurement value for one month.
The transition of is shown. (B) shows the transition of the leakage current value Ixo where the humidity H is equal to or less than the humidity management value Hn. As is clear from this, the leakage current value Ixo equal to or smaller than the control value is not related to the humidity and shows a constant value corresponding to the element 2.

In the seventh function F7 of FIG. 2, various current values and control values necessary for detecting element deterioration and insulator contamination are obtained by using the respective current values obtained in the above processing. The leak current value when the element 2 and the insulator 3 of the arrester 1 are healthy is a current value obtained by temperature-correcting the leak current when the humidity H is equal to or lower than the humidity control value Hn at the beginning of the arrester 1, that is, in the normal condition. Is calculated. From this current value Ixo, a management value (deterioration management value) In for detecting element deterioration is automatically determined by the following equation.

In = Ixo * n (n is an arbitrary constant) Next, from the current value Ixo of the healthy element 2, the capacitance component current Ic
And the resistance component current Ir. Since the ratio A: B of the capacitance component current Ic and the resistance component current Ir in the element 2 in a healthy state is known, the current value I is calculated by the following equation using this ratio.
From xo, a capacitance component current Ic of an assumed value and a resistance component current Ir of an assumed value are obtained.

Ic = Ixo * (A / (A + B)) Ir = (Ixo ² −Ic ² ) ^{1/2 Although} Ir is actually a distorted waveform, it is a value sufficiently smaller than Ic. Therefore, it can be approximated as a sine wave. As the above various current values, the element characteristics may be standardized according to the temperature at the time of arrestor introduction, and a temperature correction formula based on the measured air temperature may be applied thereafter.

The values described above are standardized at the beginning of the arrester 1 introduction. By calculating various current values and management values in this manner, various current values and management values required for element deterioration detection and insulator contamination detection are automatically registered. In addition, the various current values and control values obtained at the beginning of the arrester introduction are based on past data
It can be updated periodically by a moving average or representative value method.

When the humidity H exceeds the humidity control value Hn, an insulator surface current Ig flows. The insulator surface current Ig can be calculated from the actual measured value Iy of the leakage current obtained by the function F6 according to the following equation. Ig = ((Iy ² −Ic ² ) ^1/2 ) −Ir Also, the element current Ixo of the healthy arrester is the capacitance component current I
Since c becomes almost dominant, the element current Ixo may be simplified without separating it into the capacitance component current Ic and the resistance component current Ir, and the temperature characteristic relating to the season may be obtained by a method that can be obtained without temperature conversion. .

Ig = (Iy ² −Imi ² ) ^1/2 (Imi is the minimum average value or the representative value of the past several days) Further, the minimum value of the temperature-corrected leakage current value Ix for each day is predetermined. Remember for several days. In an eighth function F8 in FIG.
It is determined whether the zero-phase current Io is equal to or greater than a predetermined management value (identification management value) Nn. The leakage current (insulator surface current Ig) due to contamination when the insulator fouls or when the humidity rises changes almost the same in all three phases and becomes a resistive sine wave in the same phase as the voltage. When a synthesis circuit is configured, the resistance component current due to the contamination of the insulator acts to cancel. On the other hand, since the non-linear resistance leakage current at the time of element deterioration is not canceled by the three-phase synthesis circuit, the zero-phase current Io is increased even if any of the phases or each phase is simultaneously deteriorated. Therefore, by monitoring the zero-phase current Io of the three-phase synthesis circuit, deterioration of the element and contamination of the insulator can be distinguished.

A method of identifying deterioration of the element and contamination of the insulator by the function F8 will be described in detail with reference to FIGS. FIG. 5A is a waveform showing the relationship between the internal element current and the voltage phase of a sound arrester. The capacitance component current Ic has a waveform advanced by 90 ° with respect to the phase of the voltage V, and the resistance component current Ir slightly flows near the peak of the voltage phase. (B) shows a combined current Iar of the two internal element currents Ic and Ir. (C) shows the phase relationship between each phase voltage Va, Vb, Vc of the sound arrester and each phase current Ia, Ib, Ic. (D) shows the relationship between each phase voltage and the zero-phase current Io. Capacitive current Ic of each phase
Has a waveform close to a sine wave, is canceled by three-phase synthesis, and the original non-linear resistance component current Ir of each phase slightly flows to the zero-phase current Io.

FIG. 6 shows a combined current when an insulator surface current flows due to insulator contamination. As shown in (a), the insulator surface current Ig becomes a sine wave with little distortion, and has substantially the same phase as the voltage V. When the insulator fouling current flows, the leakage current I of the arrester becomes a combined current of the internal element current Iar and the surface current Ig as shown in FIG.

(C) shows each phase voltage Va, Vb, Vc and each phase current Ia, when a resistive current due to insulator contamination flows.
It shows the relationship between Ib and Ic. Since the insulator contamination basically proceeds in three phases simultaneously, the combined current Io of the insulator surface current Ig and the internal element current Iar of each phase also becomes a sine wave with little distortion. (D) shows the relationship between each phase voltage and the zero-phase current at that time. The zero-phase current Io when the arrester is sound is the same as that when there is no contamination (FIG. 5D) even when the insulator is dirty.

FIG. 7 is a waveform showing the relationship between the internal element current and the voltage phase at the time of one-phase element deterioration of the arrester.
As shown in (a), the capacitance component current Ic has a waveform advanced by 90 ° with respect to the phase of the voltage V, and the resistance component current Ir has a large value near the peak of the voltage phase. (B) shows the combined current Iar of the two internal element currents. (C) shows each phase voltage Va, Vb, Vc and each phase current Ia, Ib, Ic.
FIG. (D) shows the relationship between each phase voltage and the zero-phase current Io. As is apparent from this waveform, when the element deterioration of the arrester occurs in one phase, the zero-phase current Io shows a large value.

FIG. 8 is a waveform showing the relationship between the current and the voltage phase when one-phase element deterioration and insulator fouling occur simultaneously. As shown in (a), the insulator surface current Ig becomes a large current in phase with the voltage V because the resistance component increases. As in FIG. 7B, the internal element current Iar leads the voltage V by approximately 90 ° and becomes a large current having a distorted waveform. FIG. 8B
Shows a phase relationship between the one-phase voltage V and the combined current I.

FIG. 3C shows the phase relationship between each phase voltage Va, Vb, Vc and each phase current Ia, Ib, Ic.
The one-phase current Ia has a waveform distorted due to element deterioration. The other phase currents Ib and Ic are large currents due to insulator contamination. (D) shows the phase relationship between each phase voltage and the zero-phase current Io. Since the current components due to the insulator contamination of each phase cancel each other out by three-phase synthesis, only the component due to the one-phase element deterioration is detected as the zero-phase current Io.

FIG. 9 shows voltage and current waveforms when element deterioration occurs simultaneously in three phases (when insulator contamination does not occur). (A) shows the phase relationship between each phase voltage Va, Vb, Vc and each phase current Ia, Ib, Ic. (B) shows the phase relationship between each phase voltage and the zero-phase current Io. As is apparent from this waveform, a large zero-sequence current Io is also detected when the three phases are simultaneously degraded.

FIG. 10 shows voltage and current waveforms when element deterioration and insulator contamination occur simultaneously in three phases. (A)
Each phase voltage Va, Vb, Vc and each phase current Ia, Ib, Ic
Shows the phase relationship. (B) shows each phase voltage and zero-phase current Io.
This shows the phase relationship with. As is clear from this waveform,
Even when the elements deteriorate simultaneously, a large zero-phase current Io is detected due to the distortion of the current waveform.

If it is determined in the function F8 of FIG. 2 that the zero-phase current Io is equal to or larger than the discrimination management value Nn, a ninth function F9 is performed.
Element deterioration is detected using an element deterioration detection algorithm. FIG. 11A shows one of the measured values of the arrester leakage current.
It is a figure showing transition of a month. The scale on the horizontal axis represents one day. Leakage current fluctuates strongly due to insulator fouling and humidity. In order to eliminate the effects of insulator contamination and humidity, when the minimum value Imd of the leak current for each day stored in the function F7 described above is plotted for one month, (b) and (c)
The tendency shown in FIG. (B) shows a case where there is no element degradation, and (c) and (d) show a case where element degradation has occurred in one phase.

In the case of (c), the data of each phase is
The presence or absence of element deterioration is detected by comparing the phases. If a certain phase continues to protrude from other phases, it means that the internal element current has increased, and that phase is detected as a deteriorated phase. The same data is compared with the deterioration management value In (see function F7) as shown in (d) instead of the three-phase comparison, and if the state continues beyond the state, the phase is detected as the deteriorated phase. Display is made on the display means 15.

If it is considered that the three-phase simultaneous deterioration of the arrester is unlikely to occur stochastically, the deterioration may be judged under the condition of (c) and (d). In the example described above, the minimum value Imd of the leakage current is compared with the deterioration management value In, but the leakage current value Ixo that is stored in the function F7 and is equal to or less than the humidity management value Hn is compared with the deterioration management value In. You may do it.
When the humidity H falls below the humidity control value Hn, the leakage current Ig due to the insulator contamination becomes almost zero, so that the deterioration can be determined without being affected by the insulator contamination, and the reliability is improved.

When the zero-phase current Io is determined to be equal to or smaller than the discrimination management value Nn in the function F8 of FIG. 2, the tenth function F10
Then, insulator contamination detection is performed using an insulator contamination detection algorithm. The insulator surface current Ig (see function F7) is compared with a predetermined control value (contamination control value) Mn. If Ig> Mn, it is determined that the insulator contamination has occurred, and the display means 1
An indication of occurrence of insulator contamination is shown in FIG.

If the arrester element 2 is deteriorated and a large element current Iar flows, a large error may occur when the insulator surface current Ig is obtained. Therefore, the conversion of the insulator deterioration fouling current is not performed for that phase. If the zero-phase current Io exceeds the identification management value Nn or is smaller than the identification management value Nn, but is slightly larger, it is highly likely that a certain phase has deteriorated or is in transition to deterioration. In that case, the insulator fouling current is not determined for the phase having the highest level among the phases or the upper two phases.

As a method for determining a phase in which the insulator fouling current is not determined in the preceding paragraph, only the phase having the maximum value level may be used, or the phase at the intermediate level may be determined from the intermediate value between the maximum value phase and the minimum value phase. If it is larger, the phase of the intermediate value may be excluded. Alternatively, depending on the ratio (crest factor) between the effective value and peak value of the zero phase, a maximum of one phase is excluded, or a maximum of two phases is excluded.
It is good also as phase exclusion.

In order to be able to monitor urgent element deterioration even during detection of insulator contamination, the zero-phase current I
Deterioration is detected by the level and continuity of o. At this time, the deteriorated phase may be determined by monitoring the peak values of the phase currents Ia, Ib, and Ic. Even if the insulator contamination progresses unequally, and the leakage current due to the contamination of each phase has some variation, the degraded phase can be reliably determined by monitoring the peak value.

FIG. 12 shows a case in which the insulator surface current Ig of each phase varies due to three-phase unbalanced contamination, and a case in which deterioration occurs in the A phase having the least contamination current. (A) shows the phase relationship between the phase voltages Va, Vb, Vc and the device current Iar. (B) shows each phase voltage and each insulator surface current (insulator contamination current) IgA, IgB, Ig
The phase relationship with C is shown. (D) shows the phase relationship between each phase voltage and the combined current Io for each phase.

As shown in (c), the current Ia of the a-phase in which the insulator surface current Ig is the smallest and the element is deteriorated and the current Ic of the c-phase in which the fouling current is the largest are almost the same when compared by their effective values. . However, comparing the peak values, the a-phase current Ia is about 1.5 times larger than the c-phase current Ic.
Therefore, if the magnitude of the unbalance current of the ordinary insulator contamination and the magnitude of the deterioration management value In are considered, the deteriorated phase can be determined by monitoring the peak value of each phase even during the insulator contamination.

[0042]

According to the present invention, it is possible to obtain an arrester deterioration detecting device capable of accurately detecting element deterioration with a simple configuration and further capable of distinguishing and detecting insulator contamination.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an arrester deterioration detection device of the present invention.

FIG. 2 is a diagram showing a function of a detection unit in FIG. 1;

FIG. 3 is a view showing temperature characteristics of the arrester element of FIG. 1;

FIG. 4 is a diagram showing an arrester leakage current equal to or lower than a humidity control value.

FIG. 5 is a diagram showing a three-phase combined current when the insulator of the arrester is not contaminated.

FIG. 6 is a diagram showing a three-phase combined current when the insulator of the arrester is contaminated.

FIG. 7 is a diagram showing voltage and current waveforms when element deterioration of an arrester occurs in one phase.

FIG. 8 is a diagram showing voltage and current waveforms when element deterioration of an arrester occurs in one phase and insulator contamination occurs simultaneously.

FIG. 9 is a diagram showing voltage and current waveforms when three phases of arrester element deterioration occur simultaneously.

FIG. 10 is a diagram showing voltage and current waveforms when three-phase element deterioration and insulator contamination of an arrester occur simultaneously.

FIG. 11 is a diagram showing a determination method when element deterioration occurs in the arrester.

FIG. 12 is a diagram showing a determination method when insulator contamination occurs unbalanced and element deterioration occurs.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Arrester 2 ... Element 3 ... Insulator 4 ... Power line 5 ... Current transformer 6 ... Selector 7 ... Electric / optical converter 8 ... Optical fiber 9 ... Detector main body 11 ... Optical / electrical converter 12 ... Detecting means 13 ... Temperature Measuring means 14 Humidity measuring means 15 Display means 16 Light emitting diode 17 DC power supply V Voltage I Measured leakage current Ix Temperature-corrected leakage current Ixo Temperature-corrected when humidity falls below the control value Leakage current Io: Zero-phase current Iy: Temperature-corrected leakage current when humidity exceeds a control value In: Deterioration control value for detecting element deterioration Iar: Element current Ic: Capacitive component current Ir: Resistance component current Ia, Ib, Ic: each phase current Ig: insulator surface current Imi: minimum leakage current or minimum representative value in the past several days T: outside temperature H: humidity Mn: pollution control value Nm: identification management value Hn: humidity management

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Jin Hoshino 3-7-1, Ichibancho, Aoba-ku, Sendai City, Miyagi Prefecture Inside Tohoku Electric Power Co., Inc. (72) Inventor Naohiro Kanaman 47 Nissin Electric Co., Ltd. (72) Inventor Munetaka Saito 1219-6, Ikuhara, Minago-cho, Gunma-gun, Gunma Prefecture (72) Inventor Hideto Oki 47, Umezu Takaune-cho, Ukyo-ku, Kyoto, Kyoto, Japan F term (reference) 2G015 AA20 CA20 2G036 AA24 BA01 CA06 2G060 AA01 AA08 AA20 AB02 AE07 AE26 AF03 HA02 HC02 HC08 HC10

Claims (11)

[Claims] 1. An apparatus for detecting deterioration of a multi-phase arrester in which an element is arranged in an insulator for each phase, means for measuring a leakage current for each phase of the arrester, and measuring means for each phase. A channel selector for switching the output of each channel to a leakage current for each phase and a combined leakage current for each phase; an electrical / optical converter for converting an output signal of the channel selector into an optical signal; An optical fiber that transmits output light, and a leakage current for each phase of the multi-phase arrester and a combined leakage current of each phase are measured based on the optical signal transmitted by the optical fiber. Detecting means for detecting the deterioration of the element based on the arrestor deterioration detecting device. 2. The arrester deterioration detection device according to claim 1, further comprising a temperature measurement unit for measuring an air temperature, wherein the detection unit corrects the measured leakage current based on the air temperature. 3. The detecting means further comprises means for comparing the combined leakage current with a predetermined control value, wherein the leakage current of each phase increases substantially similarly, and the combined leakage current is When the leakage current is equal to or less than the control value, an algorithm for detecting contamination of the insulator is used, and when the combined leakage current is increased, an algorithm for detecting deterioration of the element is used. The arrester deterioration detection device according to claim 1, wherein the arrester deterioration detection device enables detection. 4. A detecting algorithm for comparing a leakage current value of each phase with each other at regular intervals and, when a leakage current value of a certain phase is prominent, identifying a phase as an element deterioration phase. The arrester deterioration detection device according to claim 3, further comprising: 5. The insulator according to claim 1, wherein the detecting means compares a leakage current value of each phase with a deterioration management value at regular intervals, and detects a phase exceeding the management value for a long time as an element deterioration phase. The arrester deterioration detection device according to claim 3, further comprising a determination algorithm that eliminates the influence of contamination. 6. The arrester deterioration detection apparatus according to claim 3, wherein the element deterioration phase is specified by using the two determination algorithms according to claim 4 and claim 5. 7. A humidity measuring means for measuring humidity, wherein the detecting means records a leakage current of each phase when the measured humidity is below a certain humidity control value, and a combined leakage current. The arrester deterioration detection device according to any one of claims 3 to 6, further comprising an algorithm for retaining data immediately before the measured humidity exceeds the control value when the measured humidity exceeds the control value. 8. The arrester deterioration detection device according to claim 7, wherein the detection means automatically determines various management values from a leakage current value when the humidity is equal to or less than the humidity management value. 9. The detecting means registers a total leakage current in a healthy state at an early stage of the operation of the arrester, and further calculates the total leakage current from the registered total leakage current at a known ratio determined by an arrestor element used. 9. The arrester deterioration detection device according to claim 8, wherein only the leakage current due to the contamination is extracted and searched for by calculating the resistance component current and the capacitance component current of the element and used for determining the contamination level. 10. The detection means updates all registered leakage currents with past data, and detects element degradation and insulator contamination using the updated leakage currents. 2. The arrester deterioration detection device according to 1. 11. The method according to claim 3, wherein said detecting means does not perform a contamination current calculation for a phase which can be assumed to have an element deterioration current flowing when extracting and calculating a leakage current due to insulator contamination from the leakage current. The arrester deterioration detection device according to any one of the preceding claims.